Subtitle display apparatus

Abstract: A character information display apparatus includes a first generator for generating a first video signal for a full-screen image including character information, a second generator for generating a second video signal for a partial-screen image including character information, a change-over switch for changing the first video signal for the full-screen image from the first generator and the second video signal for the partial-screen image from the second generator with each other, a demodulator for demodulating the character information extracted from the first video signal for the full-screen image or the second video signal for the partial-screen image output from the change-over switch, a partial-screen image processor for compressing the second video signal from the second generator in the horizontal direction and/or the vertical direction, a first compositing circuit for compositing the first video signal for the full-screen image from the first generator and the compressed video signal for the partial-screen image from the partial-screen image processor, a second compositing circuit for compositing signals from the first composite image and a character signal from the demodulator, a display device for displaying signals from the second compositing circuit, a controller provided with a key for turning ON or OFF the display of the character information, and a control processor for controlling the change-over switch under the control of the controller and for displaying the character information of the full-screen image or the partial-screen image superimposed on the full-screen image.

Description: The present invention relates to a character information display apparatus which displays character information by extracting it from a video signal wherein the character information such as caption information are multiplexed on another signal such as a conventional television signal. There are various systems for transmitting character information or graphic information by multiplexing with the vertical retrace lines of video signals such as television signals. For example, the Japanese teletext system, the English teletext system extended for an international specification, and the United States closed-caption system are known systems. In the United States closed-caption system, for instance, a caption signal wherein a binarization signal consisting the caption information is multiplexed with the image signal at its 21 vertical retrace lines at a transmitter section. The binarization signal is then extracted from the caption signal by a slice process for the caption signal at a receiver section. The binarization signal is thus decoded. The caption signal is comprised of a clock run-in signal added at the head of the caption signal for synchronizing the decoding operation of the binarization signal, a start bit following the clock run-in signal, and a character code following the start bit. To use the closed-caption it is necessary to provide a closed-caption decoder (hereinafter simply referred to as caption decoder) for decoding a multiplexed caption signal. In the U.S., the law demands to equip with a caption decoder television receivers with displays larger than or equal to the 13-inch size, since September 1993. Also, it is not possible to listen to a sound associated with the partial-screen image superimposed on the full-screen image in conventional multi-image display television receivers such as those capable of displaying a picture-in-picture (PIP) screen image or a picture-out-picture (POP) screen image. Accordingly such television receivers must be equipped with a terminal for an earphone or a headphone through which the sound associated with the partial-screen image is provided for listeners. Especially in a large size television receiver such as a projection type television receiver it is usually required to provide a wireless system for wireless transmission of the sound associated with the partial-screen image to receiver headphones, as occasion demands. Such a conventional system as described above would be accepted in a case where a plurality of viewers individually watch a full-screen image or any partial-screen image of their preference. However it is not suitable in a case where an individual desires to hear a sound associated with the partial-screen image as well as a sound associated with the full-screen image. Especially when he is wearing a headphone for hearing the sound associated with the partial-screen image, it will be difficult to listen to the sound associated with the full-screen image. On the other hand, in the conventional multi-image display type television receiver equipped with the caption decoder as described above, the closed-caption function capable of displaying captions is dedicated for the full-screen image. Thus when a viewer wishes to watch closed-caption information associated with the partial-screen image, he must change the full-screen image and the partial-screen image with each other. JP-A-05 05 369 discloses a PIP television receiver switching the display of subtitles in accordance with the sound signal supplied to the loudspeakers. FIGURE 1 shows a construction of a conventional PIP capable television receiver equipped with a caption decoder. In FIGURE 1, television signals input through an antenna 1 are distributed to a first tuner 2 and a second tuner 3. The first and second tuners 2, 3 perform tunings and video detections so as to output a video signal for the full-screen image and another video signal for the partial-screen image, respectively. A switching circuit 4 is also supplied with still another video signal through an external input terminal 5 as well as the video signals from the first and second tuners 2, 3. The switching circuit 4 is capable of selectively outputting one or two of the three video signals. Then two of the signals are output as a first video signal for the full-screen image and a second video signal for the partial-screen image from the switching circuit 4. As the external input there is a video signal applied from a recording and/or reproducing apparatus such as a video tape recorder (VTR), a laser disc (LD) and the like. Under the control of a controller 6 such as a remote controller, the switching circuit 4 performs the changeover of the full-screen image signal and the partial-screen image signal, a turning ON or OFF the display of the partial-screen image, a turning ON or OFF the mute of sound associated with the full-screen image by a control signal output from a control processor 7 such as a microcomputer. In the controller 6 there are laid-out several keys such as a key for selecting a station, an ON/OFF key for turning ON or OFF the display of the partial-screen image (e.g., PIP image), a full-screen image source changeover key, a partial-screen image source changeover key, a full-screen image and partial-screen image changeover key, an ON/OFF key for caption display, a volume control key, a sound muting key and the like. A partial-screen image signal from the switch 4 is supplied to a first compositing circuit 9 via a partial-screen image signal processor 8 for performing image compressions in the horizontal and/or vertical direction. A first compositing circuit 9 includes, for example, switch circuits, and composites the partial-screen image signal from the partial-screen image signal processor 8 with the full-screen image signal from the switching circuit 4. On the other hand, the full-screen image signal from the switching circuit 4 is also input to a caption decoder 10, so the caption information is extracted from the vertical retrace lines of the full-screen image signal and then demodulated. The demodulated caption information is then supplied to a second compositing circuit 11. The second compositing circuit 11 includes, for example, switch circuits, and composites the caption information from the caption decoder 10 with the first composite signal of the full-screen image signal and the partial-screen image signal from the first compositing circuit 9. Thus the output, i.e. a second composite signal from the second compositing circuit 11 is supplied to a display device 12 such as a cathode ray tube (CRT). The controlling circuit 7 performs tuning controls for the first tuner 2 and the second tuner 3, a control for the switching circuit 4, an ON/OFF control for the caption decoder 10, a sound muting control and the like, under the control of the controller 6. By the way in the conventional arrangement as described above, the caption decoder 10 extracts the caption information from the full-screen image signal supplied from the switching circuit 4. When a viewer wishes to watch the caption information through the partial-screen image, the conventional apparatus must confirm the caption information after displaying the full-screen image by interchanging with the partial-screen image, because its caption display capability is limited to the full-screen image. Accordingly the conventional apparatus has a drawback in that it must interchange the full-screen image and the partial-screen image with each other when wishing to use the caption display for confirming the sound associated with the partial-screen image. Further, the conventional television receiver equipped with the caption decoder has a problem that a story of images becomes ambiguous due to speeches being difficult to be caught by the viewer when a sound muting operation has been carried out at an occasion of telephone call and the like, for instance, in the state that a caption is not displayed. As described above, the conventional character information display apparatus has the problem that viewers can not directly listen the sound associated with the partial-screen image. In a manner of using a headphone, he is also impossible to listen or confirm by himself both the sounds associated with the full-screen image and the partial-screen image. When he wishes to hear the sound associated with the partial-screen image and use the caption display function, he must interchange the full-screen image and the partial-screen image with each other. And, further, the conventional character information display apparatus has a problem that a viewer can not clearly distinguish speech while sound muting is carried out when the caption is not displayed. It is, therefore, an object of the present invention to provide a character information display apparatus which is able to eliminate the drawbacks in the conventional apparatus. The present invention also has an object to provide a character information display apparatus which is able to automatically display a caption information of the partial-screen image superimposed on the full-screen image at the time of the mute of sound for allowing a viewer to listen speeches and the like. A character information display apparatus according to a first aspect of the invention is set out in claim 1. A character information display apparatus according to a second aspect of the invention is set out in claim 2. In the character information display apparatus according to the example, since the character information display apparatus has a change-over switch which selects one video signal from one for full-screen image and one for partial-screen image and inputs it to the demodulator at the first step of the demodulator, it is possible to control the change-over switch by the control processor and to display the character information of the full-screen image or the partial-screen image superimposed on the full-screen image under the control of the controller. In the character information display apparatus according to the first aspect of the present invention, since the control processor controls the change-over switch and the demodulator under the control of the controller, it turns ON or OFF the display of the character information associated with the full-screen image in response to the ON operation of character information key during the state the partial-screen image is not displayed. The character information display apparatus also performs a cyclic operation as follows; the display of the character information associated with the full-screen image → the display of the character information associated with the partial-screen image → turning OFF the display of the character information → the display of the character information of the full-screen image → ···. Accordingly, it is able to improve the operability of displaying the character information. In the character information display apparatus according to the second aspect of the present invention, however the mute of sound is carried out by pressing the sound muting key in such an occasion that a telephone rings during a viewer watching television for instance, it never fail to follow the full-screen image information even if the sound is muted because of the display of the character information of the full-screen image superimposed on the full-screen image. Additional objects and advantages of the present invention will be apparent to persons skilled in the art from a study of the following description and the accompanying drawings, which are hereby incorporated in and constitute a part of this specification. For a better understandings of the present invention and many of the attendant advantages thereof, reference will now be made by way of example to the accompanying drawings, wherein: FIGURE 1 is a block diagram showing a conventional character information display apparatus; FIGURE 2 is a diagram explaining problems in the conventional character information display apparatus; FIGURE 3 is a block diagram showing one embodiment of the character information display apparatus according to the present invention; FIGURE 4 is a diagram for explaining the operation of the character information display apparatus shown in FIGURE 3; and FIGURE 5 is a diagram explaining the operation of the character information display apparatus shown in FIGURE 3. Referring now to the attached drawings a preferred embodiment of the character information display apparatus according to the present invention will be described hereinafter. FIGURE 3 is a block diagram showing the embodiment of the character information display apparatus according to the present invention. FIGURE 3 shows a construction of a PIP capable television receiver equipped with a caption decoder, which corresponds to the conventional apparatus, as shown in FIGURE 1. Thus in FIGURE 3 the same component as the one shown in FIGURE 1 is assigned with the same reference numeral. Television signals containing a caption information input through an antenna 1 are distributed to a first tuner 2 and a second tuner 3. The first and second tuners 2, 3 perform tunings and video detections. Thus the first tuner outputs a first video signal containing the caption information for displaying a full-screen image, while the second tuner 3 outputs a second video signal containing also the caption information for displaying a partial-screen image. A switching circuit 4 is also supplied with still another video signal through an external input terminal 5 as well as the video signals from the first and second tuners 2, 3. The switching circuit 4 is capable of selectively outputting one or two of the three video signals. Then two of the signals are output as a first video signal for the full-screen image and a second video signal for the partial-screen image from the switching circuit 4. As the external input there is a video signal applied from a recording and/or reproducing apparatus such as a video tape recorder (VTR), a laser disc (LD) and the like. Under the control of a controller 6 such as a remote controller, the switching circuit 4 performs the changeover of the full-screen image signal and the partial-screen image signal, a turning ON or OFF the display of the partial-screen image, a turning ON or OFF the mute of sound associated with the full-screen image by a control signal output from a control processor 7 such as a microcomputer. In the controller 6 there are laid-out several keys such as a key for selection a station, an ON/OFF key for turning ON or OFF the display of the partial-screen image (e.g., PIP image), a full-screen image source changeover key, a partial-screen image source changeover key, a full-screen image and partial-screen image changeover key, an ON/OFF key for caption display, a volume control key, a sound muting key and the like. A partial-screen image signal from the switch 4 is supplied to a first compositing circuit 9 via a partial-screen image signal processor 8 for performing image compressions in the horizontal and/or vertical direction. A first compositing circuit 9 includes, for example, switch circuits, and composites the partial-screen image signal from the partial-screen image signal processor 8 with the full-screen image signal from the switching circuit 4. On the other hand, the full-screen image signal and the partial-screen image signal from the switching circuit 4 are supplied to input terminals a, b of a switch 13, respectively. The switch 13 then selectively outputs one of the signals to a caption decoder 10 through its output terminal c under the control of the control processor 7. The caption decoder 10 extracts the caption information from the vertical retrace lines of the full-screen image signal and then demodulates the caption information. The demodulated caption information is supplied to a second compositing circuit 11. The second compositing circuit 11 includes, for example, switch circuits, and composites the caption information from the caption decoder 10 with the first composite signal of the full-screen image signal and the partial-screen image signal from the first compositing circuit 9. Thus the output, i.e. a second composite signal from the second compositing circuit 11 is supplied to a display device 12 such as a cathode ray tube (CRT). The controlling circuit 7 performs tuning controls for the first tuner 2 and the second tuner 3, a control for the switching circuit 4, an ON/OFF control for the caption decoder 10, a sound muting control and the like, as well as the control of the switch 13, under the control of the controller 6. In the above construction, the switch 13 is coupled to the input of the caption decoder 10 for selectively transmitting one of the full-screen image signal on its input terminal a and the partial-screen image signal on its input terminal b to the caption decoder 10, under the ON/OFF control of a caption key on the controller 6. Thus when the switch 13 selects the input terminal a, the caption information in the full-screen image signal is displayed on the full-screen image. While when the switch 13 selects the input terminal b, the caption information in the partial-screen image signal is displayed on the full-screen image. The control processor 7 controls the switching circuit 4, the switch 13 and the caption decoder 10 under the control of a partial-screen image display (PIP) key and the caption key on the controller 6. According to the control operations of the control processor 7, the character information display apparatus of the television receiver performs operations as follows. When the switching circuit 4 so controls that the partial-screen image signal will not be output by turning OFF the partial-screen image display (PIP) key (i.e., the partial-screen image is not displayed), the caption information in the full-screen image is turned ON or OFF, as shown in FIGURE 4(a), since the switch 13 is changed in response to the operation of the caption key on the controller 6. And when the partial-screen image signal is selected at the switching circuit 4 in response to the ON operation of the partial-screen image display (PIP) key (i.e., the display of the partial-screen image is intended), it performs a cyclic operation as follows: the display of the caption associated with the full-screen image → the display of the caption associated with the partial-screen image → turning OFF the display of the caption → the display of the caption associated with the full-screen image ···, as shown in FIGURE 4(b), since the switch 13 is changed so as to control the output of the caption decoder 10 in response to the operation of the caption key on the controller 6. The control processor 7 also controls the switching circuit 4, the switch 13, and the caption decoder 10 under the control of a sound muting key on the controller 6. According to the control operations of the control processor 7, the character information display apparatus of the television receiver performs operations as follows. When the sound muting key is pressed in the state that the full-screen image is displayed (containing the state that both the full-screen image and the partial-screen image are displayed and the state that the caption information in partial-screen image signal is displayed on the full-screen image), as shown in FIGURE 5, the mute of sound associated with the full-screen image is carried out at the switching circuit 4 (tuning ON the mute), at the same time the switch 13 is changed to the input terminal a for receiving the full-screen image signal, thus the caption information associated with the full-screen image being displayed. When the sound muting key is pressed again the mute of sound is turned OFF at the switching circuit 4 (a sound is produced), and at the same time the output of the caption decoder is so controlled to turns OFF the display of the caption information (the caption information disappears). The caption information as the same as before can be activated again by the operation of the sound muting key on the controller, regardless of whether the caption information is associated with the full-screen image or the partial-screen image. The present invention is not limited to the television receiver equipping with the United States system closed-caption decoder. For example, the present invention can be applied to the television receiver equipping with the Japanese system sound multiplex broadcast decoder. As described above, the present invention can provide an extremely preferable character information display apparatus which displays a character information (e.g., captions) of the partial-screen image in listening the sound associated with the full-screen image. The present invention can also provide the character information display apparatus on which viewers can enjoy both the full-screen image and the partial-screen image. On the other hand, the present invention can provide the character information display apparatus in which viewers can confirm captions representing speeches since the character information in the full-screen image signal is automatically displayed on the full-screen image when the sound associated with the full-screen image is muted. While there have been illustrated and described what are at present considered to be preferred embodiments of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made. and equivalents may be substituted for elements thereof without departing from the true scope of the present invention. In addition, many modifications may be made to adapt a particular situation or material to the teaching of the present invention without departing from the central scope thereof. Therefor, it is intended that the present invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out the present invention, but that the present invention includes all embodiments falling within the scope of the appended claims.

Claims: A character information display apparatus comprising: first generator means for generating a first video signal for a first full-screen image including character information; second generator means for generating a second video signal for a second image including character information; change-over means for exchanging the first video signal for the full-screen image from the first generator means with the second video signal for the second image from the second generator means; demodulation means for demodulating the character information extracted from the first video signal for the full-screen image or the second video signal for the second image output from the change-over means; partial-screen image processing means for compressing the second video signal from the second generator means in the horizontal direction and/or the vertical direction to form a partial-screen image; first compositing means for compositing the first video signal for the full-screen image from the first generator means and a compressed video signal for the partial-screen image from the partial-screen image processing means to form first composite signals for a first composite image; second compositing means for compositing the first composite signals and a character signal from the demodulation means to form second composite signals for a second composite image; display means for displaying the second composite signals from the second compositing means; controller means provided with a first key for turning ON or OFF a display of the partial-screen image and a second key for turning ON or OFF a display of the character information; control processor means for controlling the second generator means, the change-over means and the demodulation means under the control of the controller means, and further for turning ON or OFF the display of the character information corresponding to the full-screen image when the second key is pressed and the first key is OFF and the partial-screen image is not displayed; and for controlling a cyclic operation, namely: turning ON the display of the character information corresponding to the full-screen image, turning ON the display of the character information corresponding to the partial-screen image, and turning OFF the display of the character information when the second key is pressed and the first key is ON and the partial-screen image is displayed. A character information display apparatus comprising: first generator means for generating a first video signal for a first full-screen image including a character information; second generator means for generating a second video signal for a second image including character information; change-over means for exchanging the first video signal for the full-screen image from the first generator means with the second video signal for the second image from the second generator means; demodulation means for demodulating the character information extracted from the first video signal for the full-screen image or the second video signal for the second image output from the change-over means; partial-screen image processing means for compressing the second video signal from the second generator means in horizontal and/or vertical direction to form a partial-screen image; first compositing means for comprising the first video signal the for full-screen image from the first generator means and the compressed video signal for the partial-screen image from the partial-screen image processing means to form first composite signals for a first composite image; second compositing means for compositing the first composite signals and a character signal from the demodulation means to form second composite signals for a second composite image; display means for displaying the second composite signals from the second compositing means; controller means provided with a first key for turning ON or OFF the partial-screen image display, a second key for turning ON or OFF the display of the character information, and a third key for turning ON or OFF the sound muting; and control processor means for controlling the first and the second generator means under the control of the controller means, the change-over means, and the demodulation means and further for turning ON or OFF the display of the character information corresponding to the full-screen image whenever the second key is pressed when the first key is OFF and a partial-screen image is not displayed, for controlling a cyclic operation, namely: turning ON the display of the character information corresponding to the full-screen image, turning ON the display of the character information corresponding to the partial-screen image, and turning OFF the display of the character information when the second key is pressed and the first key is ON and the partial-screen image is not displayed; and for turning ON or OFF the character information corresponding to a full-screen image at the same time as turning the mute of sound ON or OFF when the third key is pressed. A character information display apparatus as claimed in claim 1 or 2, wherein the character information includes a closed-caption signal.

Inventors: ISOE YOUICHI, MORISHITA TATSUO, ISOE, YOUICHI, MORISHITA, TATSUO, ISOE, YOUICHI, C/O INTELLECTUAL PROPERTY DIV., MORISHITA, TATSUO, C/O INTELLECTUAL PROPERTY DIV.
Applicants: TOSHIBA KK, KABUSHIKI KAISHA TOSHIBA
Application year: 1994
Main classification: H04N5
IPC codes: H04N5, G09G5